This invention relates to endless power transmission belts.
So-called raw-edged endless, trapezoidal power transmission belts are well known in the art. These belts are made primarily of elastomeric material and generally comprise a helically-wound load-carrying cord and may also comprise one or more layers of fabric. The elastomeric material may also have a plurality of fibers dispersed therethrough.
During operation of such belts around associated pulleys or sheaves, there is repeated flexing and imposition of stresses thereon, leading to a buildup of heat within the belt, which may ultimately cause premature belt failure. This problem becomes increasingly acute with belts employed upon motor vehicle engines, since the trend appears to be toward higher engine compartment temperatures. One approach to providing a cool running belt is disclosed in U.S. Pat. No. 1,860,269. That belt has a plurality of transverse apertures or perforations extending from one side surface of the belt to the other, and arranged in spaced relation the full length of the belt.
Heretofore, it is also known to incorporate graphite into at least one of the elastomeric layers of a belt in order to reduce the belt to sheave coefficient of friction. This feature is disclosed in U.S. Pat. Nos. 4,024,773 and 4,031,768.
It has now been discovered that the heat buildup in a raw-edge power transmission belt can be reduced by incorporating a particular type of graphite into at least one layer of the belt. This heat-reducing feature is not seen when ordinary graphite is used.
Accordingly, it is an object of the present invention to provide a novel, cool running, raw-edge, endless power transmission belt.
Another object of the present invention is to provide a method for making the above belt.
Other objects, aspects and advantages of the present invention will be apparent to those skilled in the art from the following specification, the appended claims and the attached drawing.